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For example, a lock file might govern access to a set of related resources, such as several different files, directories, a group of disk partitions, or selected access to higher level protocols like servers or database connections. When using lock files, care must be taken to ensure that operations are atomic. To obtain a lock, the process ...
A memory-mapped file is a segment of virtual memory [1] that has been assigned a direct byte-for-byte correlation with some portion of a file or file-like resource. This resource is typically a file that is physically present on disk, but can also be a device, shared memory object, or other resource that an operating system can reference through a file descriptor.
In computer science, a readers–writer (single-writer lock, [1] a multi-reader lock, [2] a push lock, [3] or an MRSW lock) is a synchronization primitive that solves one of the readers–writers problems. An RW lock allows concurrent access for read-only operations, whereas
In this solution of the readers/writers problem, the first reader must lock the resource (shared file) if such is available. Once the file is locked from writers, it may be used by many subsequent readers without having them to re-lock it again. Before entering the critical section, every new reader must go through the entry section. However ...
FCBs were thus superseded by file handles, as used on UNIX and its derivatives. [3] File handles are simply consecutive integer numbers associated with specific open files. If a program uses the newer file handle API to open a file, the operating system will manage its internal data structure associated with that file in its own memory area.
In common region-locked DVDs (but not in RCE-DVDs), the region code is stored in the file "VIDEO_TS.IFO" (table "VMGM_MAT"), byte offsets 34 and 35. [13] The eight regions each correspond to a value which is a power of 2: Region 1 corresponds to 1 (2 0), Region 2 to 2 (2 1), Region 3 to 4 (2 2), and so on through Region 8, which corresponds to ...
POSIX also provides the mmap API for mapping files into memory; a mapping can be shared, allowing the file's contents to be used as shared memory. Linux distributions based on the 2.6 kernel and later offer /dev/shm as shared memory in the form of a RAM disk , more specifically as a world-writable directory (a directory in which every user of ...
From 1979 to 1999 the canal itself was under joint U.S.-Panamanian control. Since 1980, it took the country code of Panama (PA). Retired. Panama Canal Zone area was returned to Panama. The area is now under WAC 162. 1 162 16201 Panama Middle America Panama Independent State in the World Panama PA 1950-01-01 1 174 17401 San Andres Island Middle ...